Improvising Over Chords

I think of the notes of resolution, and emphasis, and relationships changing
with the chord progression.
What I mean is, when soloing during a I chord, I'll emphasize notes that
are in the (e.g. blues) scale of the I chord--and more than that, I'll
lean a bit harder on the notes that are actually in the I7 chord.

When the IV chord comes around, I'll switch and emphasize notes in the
(e.g. blues) scale of the IV chord with further emphasis on the IV7 chord
notes. Same for the V chord. So, to me, one of the first "theory" things
to learn (or learn to hear) is the notes in the I, IV, and V chords--then
adding the rest of the notes in the (e.g. blues) scales for those chords.

By way of example, consider the key of C. The I, IV, and V chords are
C, F, and G--with the 7th we're talking C7, F7, and G7, which have these
notes:

C7: C E G BbF7: F A C EbG7: G B D F
The chords don't change just because you play the notes in a different
order (though they are sometimes called "inversions" of the root chord).
So, let me line up these chords in pairs, to show where notes overlap:
(I) C7: C E G Bb(IV) F7: C Eb F A
So you see a couple of things.

The root note, C, of the I chord, C7, is the same as the 5 (dominant) of
the IV chord, F7.

The 7 note of the IV chord, Eb, is the same as the all-important-in-blues
flat 3rd of the I chord (3rd is E, so flat 3rd is Eb).

From listening, we know that the 7 note and the flat 3rd are "notes of
tension"--we want to hear them resolve. So, depending on where you are
in the chord progression you resolve differently from the same note (Eb,
or the 2nd position 3' [3 draw bend])--either to IV (F7) chord (or scale)
notes, or I (C7) chord (or scale) notes. But, look here: the C note
is shared between these two chords. So you can resolve Eb to C over either
the I=C7 chord or the IV=F7 chord. For 2nd position, that's 3' to
2 (3 draw bend to 2 draw). Ever use that?! Of course! It fits
in so many places. This is why! In blues, we're mostly on the I and
IV chords, with occasional ventures into the V.
(I) C7: C E G Bb(V) G7: D F G B
The I and V chords share the 5 note of the I chord (the G of the C7 chord)
and the root note of the V chord (the G of the G chord). And, the flat
3rd--here the Bb--of the V chord (the G7) is the same as the 7 note of
the I chord. Okay, we've seen this before. The flat 3rd and the 7th are
both notes of tension that want to resolve, either up from the 7 to the
1 (Bb to C) or from the flat 3rd to the 3rd as a transition, or to the
root of the 5--so Bb to B, or Bb to G. In second position, that's 2'' 2
(2 draw double bend to 2 draw) as 7th to root of the 1 chord, or 2'' 1
(2 draw full bend to 1 draw) for flat 3rd to tonic of the V chord.
(IV) F7: F A C Eb (V) G7: F G B D
The F7 and G7--IV and V chord--share the F note, the root of the IV and
the 7 of the V. The 7 is a note of tension, the root, a note of resolution.
This going from tension to resolution is the heart of blues.
But here, you don't have to change notes! You can play the same note, and
the chord progression will go from IV--V, resolved to tense, or from V--IV,
tense to resolved. We're talking about the 4> (four blow) here for 2nd
position.
(IV) F7: F A C Eb (I) C7: G Bb C E (V) G7: G B D F
So the C7 chord sits nicely between the F7 and G7, sharing the C note with
the F7, and the Eb as the "blue note" flat 3rd; and the G note with the
G7 chord, with the Bb as the G7 chord's "blue note" flat 3rd.

Learning other chords, including bigger 4 and 5 note chords, can show
you what notes can be used to transition smoothly from one chord to another,
and provides many ideas for improvisation.

Root Notes Are Anchors

The root note of a chord is the key note, and it anchors any improvisation
over that chord. Musical lines either start on the root note or head
to a root note, either of the current chord or the next chord in the chord
progression. Arpeggios begin on the
root note, scales go from root (tonic) to root, and interval relationships
are revealed based on the root note. For example, the flat third
blue note is a minor third from the root note, e.g. Eb in a C chord.

Since the I, IV, and V chords are the most often used chords in blues,
and most music, it is important to be thoroughly familiar
with where the root notes are for these chords. Since 2nd
position cross harp is the most used playing position, it is very important
to know where all the root notes are on the harp for all these three chords
in 2nd position.

The root notes for the I chord in 2nd position are:2, 6>, 9> (and 3>)

The root notes for the IV chord in 2nd position are:1>, 4>, 7>, 10>

The root notes for the V chord in 2nd position are:1, 4, 8

Practice playing these root notes by themselves. First work on
the root notes for the I chord. Play 2, 6>, and 9> over and over
until you can hit them cleanly every time without looking. Pick up
a harp and close your eyes. Can you play the 2 draw, 6 blow, and
9 blow without looking or playing any other notes? Keep working on
it until you can. Do the same for the IV and the V chord.

Having a firm grasp of these chordal root notes will help anchor your
internalized image of the harp, as well as anchoring your
improvisations to the underlying chords. You will be able
to know exactly where the octaves span on your harp, and where to play
to stay in a certain octave or pitch range. You will be better able
to feel how to move phrases around on the harp, from low to middle to high,
and in general it will help you know your way around the harp better.
On other instruments you can often see where you are.. see where the octaves
are, but not so on the harp. It has to be internalized--all our vision
is inner. Practice these root notes to help provide
anchor points for your inner vision.

Play through the "Root Note Blues" tabbed out here. Remember,
the dots (.) are there to remind you hold that note a bit to swing the
beat. No, it's not the most interesting blues you've ever heard--but
it is clearly recognized as a standard blues because the chords are suggested
by their root notes.

Root Note Blues

I

Bar 1

Bar 2

Bar 3

Bar 4

1 &

2 &

3 &

4 &

1 &

2 &

3 &

4 &

1 &

2 &

3 &

4 &

1 &

2 &

3 &

4 &

2.2

6>.6>

9>.9>

6>.6>

2.2

6>.6>

2.2

6>.6>

2.2

6>.6>

9>.9>

6>.6>

2.2

9>.9>

6>.6>

2.2

IV

I

Bar 5

Bar 6

Bar 7

Bar 8

1 &

2 &

3 &

4 &

1 &

2 &

3 &

4 &

1 &

2 &

3 &

4 &

1 &

2 &

3 &

4 &

1>.1>

4>.4>

7>.7>

10>.10>

1>.1>

4.>4>

7>.7>

4>.4>

2.2

6>.6>

9>.9>

6>.6>

2.2

6>.6>

2.2

6>.6>

V

IV

I

V

Bar 9

Bar 10

Bar 11

Bar 12

1 &

2 &

3 &

4 &

1 &

2 &

3 &

4 &

1 &

2 &

3 &

4 &

1 &

2 &

3 &

4 &

1.1

4.4

8.8

4.4

1>.1>

4>.4>

7>.7>

4>.4>

2.2

6>.6>

2.2

9>.9>

8.8

4.4

1

_

It is easy to make simple changes to the Root Note Blues to produce
something a little more interesting. Notice the key role played by
the root notes on beats 1 and 3, and the way that beats 2 and 4 lead to
and from the root notes. Also notice the rhythmic interest added
by the triplet eighths (3 notes per beat) on the second and forth beat.
The triplets add to the feeling of "going somewhere" and the root notes
add to the feeling of "getting where you're going".